Propeller PCB Layout Template and First Attempt

Does someone have a template Propeller PCB layout that will work with one of the free layout tools? I'd like to try my hand at designing a simple Propeller board and want to start with a working circuit. I'm really just interested in the Propeller, EEPROM, crystal, a PropPlug port, and any required passives.

The thread link above contains DipTrace files for a stripped down Quickstart board. I also have the Propeller Platform SD board files. Both use the QFP, not DIP obviously.
I can also give you my M44D40+ DipTrace file. It can use both the DIP and QFN.

Thanks for the links. I'm not sure I need auto routing. I might be able to modify the PropellerPlatform layout to meet my needs. I just wondered if I was missing something.

Another thing I wasn't sure about is the difference between ExpressPCB's "Classic" and "Plus" programs. I downloaded the Plus version and it seemed to be able to load the Propeller Platform files. Should I be using the classic version instead?

As an FYI regarding ExpressPCB, if you wanted your gerber to go to another fab house, you will have to pay for it. I don't believe there are any options for you to obtain the design data itself in a transferable format.

Personally, I prefer DipTrace as a free design software. It's very easy to use and several of Parallax's open source designs are done with DipTrace, so it is easy to harvest a board you are familiar with to learn. I actually have the Full version, but the Freeware version has lots of ability.

Thanks for the links. I'm not sure I need auto routing. I might be able to modify the PropellerPlatform layout to meet my needs. I just wondered if I was missing something.

Another thing I wasn't sure about is the difference between ExpressPCB's "Classic" and "Plus" programs. I downloaded the Plus version and it seemed to be able to load the Propeller Platform files. Should I be using the classic version instead?

The "Plus" to me.. is harder to navigate, but does the same as the old program. I'll use to old program if I need to knock out a simple prototype. That's what it is good for.

Okay, I'm sure this is a dumb question but does ExpressPCB auto-route or do you have to manually connect everything? Also, is there a way to display the schematic that corresponds to a layout?

You could also check into KiCAD (open source CAD) ?
That has a very capable shove router, which is what you really need for compact PCB designs. You steer the trace and the router pushes traces & vias to make room.
The V5 release is very close, but the nightly builds are quite stable.

I found this breakout board that I think will work with my encoder. Unfortunately, the board design was done using Eagle. Is there someone here who has Eagle and can read this file and export it in a format that DipTrace can use?

I found this breakout board that I think will work with my encoder. Unfortunately, the board design was done using Eagle. Is there someone here who has Eagle and can read this file and export it in a format that DipTrace can use?

Duh. I just noticed that DipTrace can import this file directly. Now I just have to figure out how to make this into a component so I can include it in another design.

Personally, I prefer DipTrace as a free design software. It's very easy to use and several of Parallax's open source designs are done with DipTrace, so it is easy to harvest a board you are familiar with to learn. I actually have the Full version, but the Freeware version has lots of ability.

Diptrace is only free below some limit, and that seems a quite (deliberately) low limit. 300 pins is not very many.

Parallax uses Altium internally, and that can export via PCAD into kiCAD (which is free, open-source, with no limits)

I found this breakout board that I think will work with my encoder. Unfortunately, the board design was done using Eagle. Is there someone here who has Eagle and can read this file and export it in a format that DipTrace can use?

I see that the Propeller Platform board uses an LD1085 5V regulator and an LD1086 3.3V regulator. Is there a reason to use a different regulator for 5V and 3.3V? There is a 3.3V version of the LD1085 as well.

Also, when I place the TO-220 version of the LD1085 (actually, LT1085) on my PCB it seems to indicate that the part will be mounted vertically. How do I get a footprint that lies flat so that the heat sink is against the PCB?

And, what header part should I used for the PropPlug. I'm not sure how to decipher part numbers like 644456-4. The -4 part I get but how do I intensify a mail header with the right spacing for the PropPlug?

The SMT version of the LT1085 is in a D2Pak or DD package. D2Pak is a more common name, but not sure what the software will call it. The 644456-4 is a TE part number (the actual part number is 3-644456-4) and yes, it is hard to choose packages using MPNs like that when you don't have any way to do a parametric search. However, you can use Digikey's or Mouser's parametric search to narrow down options and then check to see what is already in the software. Making parts in DipTrace can be tricky at first, but once you make a couple, they are really simple. The hardest part is interpreting manufacturer dimensions when the leads are not spaced to a standard.

JMG, yeah, I knew it was 300, but I haven't had to count pins in a while, so I wasn't relating the 300 to any designs. I am very aware of the design you mentioned, and it has a high number of pins for what it is, so yes, it wouldn't work for DipTrace Free. I know that Parallax is using Altium now, but they still have a lot of DipTrace files available on their site. Since I have DipTrace full and know it well enough for designs, I haven't bothered checking out KiCad further. Plus, I have full access to Altium through work (and a friend that knows it very well) if I did want to learn another EDA software.
KiCad is becoming a reputable piece of software though. When I lst checked on their forums (about 6 months ago) the negative thing were similar to the 2.x versions of DipTrace (which is now at 3.2), so I could see DipTrace losing ground if KiCad keeps its current pace of improvement.

I'm trying to use through-hole parts at present just to make this first PCB easy. I think I figured out that the header part I mentioned will work with the PropPlug. I've done most of the schematic and am ready to move to PCB layout. I suspect that's the harder part.

Here is my first attempt at a schematic. This board contains a basic Propeller circuit plus two outputs to drive WS2812 LED chains. It also contains a rotary encoder with an RGB LED and push button switch and a connector for a 16x2 parallel LCD display. Does anyone see any red flags before I try to lay out a PCB? One thing I'm really not sure of is how to get the bypass caps positioned correctly on the PCB. I just have them attached to the power and ground nets in the schematic.

Dave,
I seem to recall there used to be a whole panel of prop boards that you could use either directly or as a model for your project, actually many models. There should be quite a few examples of how different people have designed their prop boards. Can't recall what that board was called, but someone here may remember or have a link to it.

Dave,
I seem to recall there used to be a whole panel of prop boards that you could use either directly or as a model for your project, actually many models. There should be quite a few examples of how different people have designed their prop boards. Can't recall what that board was called, but someone here may remember or have a link to it.

FF

I remember that too. I'm not sure if the designs for those boards were available but I didn't order the panel. I suspect that the Propeller Platform was one of the designs and that is the one I used as a reference as suggested by someone else here. Right now I'm having a hard time figuring out how to get DipTrace to let me tell it the dimensions of the board that I want to use. I can draw a border but there doesn't seem to be a way to say, for example, that I want to constrain my design to a board that measures 3.8" x 2.5" (what ExpressPCB wants for its mini board).

Dave,
I seem to recall there used to be a whole panel of prop boards that you could use either directly or as a model for your project, actually many models. There should be quite a few examples of how different people have designed their prop boards. Can't recall what that board was called, but someone here may remember or have a link to it.

Here is my first attempt at a schematic. This board contains a basic Propeller circuit plus two outputs to drive WS2812 LED chains. It also contains a rotary encoder with an RGB LED and push button switch and a connector for a 16x2 parallel LCD display. Does anyone see any red flags before I try to lay out a PCB? One thing I'm really not sure of is how to get the bypass caps positioned correctly on the PCB. I just have them attached to the power and ground nets in the schematic.

Those LT1085/LT1085 are not cheap as regulators go - do you need a lot of current / voltage ?

I like the look of the new ST LDL1117 series.
Those are like an improved LM317, with fixed outputs, and much lower Iq and low drop out.
Low cost in a SOT223, and with high PSRR, good to 18V, so not as high V or W as the LT1086, but fine for most 9~12V plug power sources.
The low dropout means you can power this from 5V

Here is my first attempt at a schematic. This board contains a basic Propeller circuit plus two outputs to drive WS2812 LED chains. It also contains a rotary encoder with an RGB LED and push button switch and a connector for a 16x2 parallel LCD display. Does anyone see any red flags before I try to lay out a PCB? One thing I'm really not sure of is how to get the bypass caps positioned correctly on the PCB. I just have them attached to the power and ground nets in the schematic.

Those LT1085/LT1085 are not cheap as regulators go - do you need a lot of current / voltage ?

I like the look of the new ST LDL1117 series.
Those are like an improved LM317, with fixed outputs, and much lower Iq and low drop out.
Low cost in a SOT223, and with high PSRR, good to 18V, so not as high V or W as the LT1086, but fine for most 9~12V plug power sources.
The low dropout means you can power this from 5V

The Propeller Platform schematic I was working from used LD1085 and LD1086. I couldn't find those in the libraries but did find the "LT" parts. I think they have the same pinout so I can always substitute other regulators. I might be interested in fairly high current to allow driving lots of WS2812 LEDs although I'm also providing a way to supply 5V from an external power supply as well.

Here is my first attempt at a schematic. This board contains a basic Propeller circuit plus two outputs to drive WS2812 LED chains. It also contains a rotary encoder with an RGB LED and push button switch and a connector for a 16x2 parallel LCD display. Does anyone see any red flags before I try to lay out a PCB? One thing I'm really not sure of is how to get the bypass caps positioned correctly on the PCB. I just have them attached to the power and ground nets in the schematic.

Those LT1085/LT1085 are not cheap as regulators go - do you need a lot of current / voltage ?

I like the look of the new ST LDL1117 series.
Those are like an improved LM317, with fixed outputs, and much lower Iq and low drop out.
Low cost in a SOT223, and with high PSRR, good to 18V, so not as high V or W as the LT1086, but fine for most 9~12V plug power sources.
The low dropout means you can power this from 5V

The Propeller Platform schematic I was working from used LD1085 and LD1086. I couldn't find those in the libraries but did find the "LT" parts. I think they have the same pinout so I can always substitute other regulators. I might be interested in fairly high current to allow driving lots of WS2812 LEDs although I'm also providing a way to supply 5V from an external power supply as well.

Don't get caught trying to drive many 100's of milliamps from a 5V linear regulator just because the regulator specs says it can. The more current it handles times the more voltage it is "dropping" is the power it must dissipate which in such a small package and lack of heatsinking can be a source of smoke and woe. So 12V to 5V at a measly 100ma = 7x0.1 = 700mW which is still very hot for small regulators. Use an external 5V or use a switching regulator. Personally I switch down to 5V and use small SOT89 packs or even SOT23 for my 3.3V. There are plenty of cheap 3-pin "7805" style switcher modules available these days, they run nice and cool and being switchers they will draw less current from say 12V then they supply at 5V etc. Rough rule is say 85% efficiency so 5V @ 500ma = 2.5W divided by 12V and by 0.85 is approx 245ma @12V.

Here is my first attempt at a schematic. This board contains a basic Propeller circuit plus two outputs to drive WS2812 LED chains. It also contains a rotary encoder with an RGB LED and push button switch and a connector for a 16x2 parallel LCD display. Does anyone see any red flags before I try to lay out a PCB? One thing I'm really not sure of is how to get the bypass caps positioned correctly on the PCB. I just have them attached to the power and ground nets in the schematic.

Those LT1085/LT1085 are not cheap as regulators go - do you need a lot of current / voltage ?

I like the look of the new ST LDL1117 series.
Those are like an improved LM317, with fixed outputs, and much lower Iq and low drop out.
Low cost in a SOT223, and with high PSRR, good to 18V, so not as high V or W as the LT1086, but fine for most 9~12V plug power sources.
The low dropout means you can power this from 5V

The Propeller Platform schematic I was working from used LD1085 and LD1086. I couldn't find those in the libraries but did find the "LT" parts. I think they have the same pinout so I can always substitute other regulators. I might be interested in fairly high current to allow driving lots of WS2812 LEDs although I'm also providing a way to supply 5V from an external power supply as well.

Don't get caught trying to drive many 100's of milliamps from a 5V linear regulator just because the regulator specs says it can. The more current it handles times the more voltage it is "dropping" is the power it must dissipate which in such a small package and lack of heatsinking can be a source of smoke and woe. So 12V to 5V at a measly 100ma = 7x0.1 = 700mW which is still very hot for small regulators. Use an external 5V or use a switching regulator. Personally I switch down to 5V and use small SOT89 packs or even SOT23 for my 3.3V. There are plenty of cheap 3-pin "7805" style switcher modules available these days, they run nice and cool and being switchers they will draw less current from say 12V then they supply at 5V etc. Rough rule is say 85% efficiency so 5V @ 500ma = 2.5W divided by 12V and by 0.85 is approx 245ma @12V.

Initially I was only hoping to use the onboard 5V supply for testing small numbers of LEDs. That's why I added the ability to provide an external 5V supply. However, I'm now wondering if the three pin header that I have for selecting between the onboard and an external 5V is adequate for the larger current that might be drawn if I use the external supply. I suppose I have to make sure the traces going to that header are heavier than the typical ones on the PCB but how much current can the header itself handle?